Many took to social media to characterize the major restrictions as hypocritical in comparison to gun laws, as the gunman, Omar Saddiqui Mateen, reportedly bought an AR-15-semiautomatic assault rifle and a handgun within days of the shooting.

It’s legal to buy an AR-15 assault rifle. It’s illegal for a gay man to donate blood to victims of the massacre. The world makes no sense.

When the FDA eased the ban in December of any blood donations from gay and bisexual men, its reception was lukewarm, as Lucy Schouten reported for The Christian Science Monitor at the time. The FDA enacted the all-out-ban 30 years ago in an effort to stop the spread of HIV, the virus that causes AIDS, and an illness the world knew little about then.

This past year, the FDA said the full ban was no longer supported by science, and lifted it, largely because of a compelling study by the Australian government. Australia, along with Britain and New Zealand, preceded the United States in reducing the lifelong ban on gay men donating blood.

"Ultimately, the 12-month deferral window is supported by the best available scientific evidence, at this point in time, relevant to the US population," Peter Marks, deputy director of the FDA's biologics division, said in a statement at the time.

Immediately following the FDA's announcement, members of the Congressional LGBT Equality Caucus said the restrictions cried hypocrisy then too, but for a different reason.

"It is ridiculous and counter to the public health that a married gay man in a monogamous relationship can't give blood, but a promiscuous straight man who has had hundreds of opposite-sex partners in the last year can," said Rep. Jared Polis (D) of Colorado, a co-chair of the Congressional LGBT Equality Caucus.

Other countries have adopted a more flexible approach. Italy, for instance, performs an "individual sexual risk assessment" for gay men, which is basically a questionnaire that asks the donor about their history of unprotected sex, according to Wired.com. Since Italy started to screen donors this way in 2001, the country has experience no major uptick in HIV infections.

The US screens all donated blood for HIV, and asks those who have traveled to areas with outbreaks of the Zika virus, show symptoms associated with the infection or have had sexual contact with someone exposed to the virus to delay donating blood.

As science offers more clarity about the risks involved with gay blood donors, members of the LGBT community have said the Pulse shooting has placed their struggles in stark relief.

"Today is a painful reminder that there are still so many battles left for us to fight. The oppressive, outdated policy on queer blood is one, and it must come to an end," John Paul Brammer, an Oklahoma blogger who covers LGBT activism, wrote in an op-ed for The Guardian. "Today, like so many others in my community, I am overcome with a sense of helplessness. I am overcome with the urge to do something, anything, to help the victims and their families."